Hello shakefour,

Being able to send invoices through a text message would be a great advantage for easy sending of transactions. While this option isn't available in QuickBooks Online, I have a workaround for you, though.

You can copy the link and then send the link to your customer via text message. To get the link, click Save and share link on the Invoice page. I'll add this screenshot as your visual guide:

Furthermore, you can check this article on how to let customers pay their invoices online: Take and process payments online.

You can always post in the forum whenever you have concerns about sending invoices.